1. Field of the Invention
The present invention relates to a base station of a radio system comprising: a central processing unit which includes control and maintenance means for controlling the base station in response to control signals transmitted from a base station controller, and at least one baseband frame unit for generating and supplying baseband signals further via a switching means alternatively to either of at least two radio channel units of the base station in response to telecommunication signals transmitted from the base station controller and for processing baseband signals transmitted from said radio channel unit and for supplying them further to the base station controller, and means for establishing a telecommunication connection with radio signals to radio units in the radio coverage area of the base station.
This invention primarily relates to variations in the capacity need of different parts of the geographical area covered by the cellular radio system. For example, in business centres considerably more traffic capacity is needed during daytime than in the evening. Correspondingly, the situation in suburban areas may be such that during daytime the capacity need is very small but in the evenings it becomes great when the residents return home from their places of work. If the capacity of the cellular radio system is dimensioned under these circumstances in accordance with the capacity need peaks, it will lead to a situation in which a considerable portion of the capacity of the system remains unused for the most part of the day.
2. Description of Related Art
Solutions are known previously in which calls of an adjacent cell are transmitted by using an antenna which can be temporarily directed thereto. In that case the coverage area of the adjacent cell cannot usually be completely covered.
Solutions are also known previously in which separate additional channel units are used by means of a relay-type of switchings, that is, the capacity of the additional channel unit shifts from one sector or cell to another in such a way that its antenna connection is changed by means of relay switchings. In this case, the geographical area on which capacity variation can be attained is very small as the RF signal from the antenna connection of the additional channel unit cannot be transferred very far e.g. by means of cables without the signal attenuation being significant in the cable. That means that for practical reasons, the alternative transmission antennas to which the additional channel unit can be switched should situate very close to one another.